1. Field of the Invention
The present invention relates to a vacuum retaining device, and more particularly to a vacuum retaining device capable of reuse. The vacuum retaining device can keep the shape and efficiency of a sealing rim for a long time. When it is detached from a surface to be adhered, the vacuum retaining device can be operated conveniently.
2. Description of the Prior Art
In general, it is more difficult to use a screw or a nail on a wall adhered with tiles or a glass surface for hanging or retaining some articles. A vacuum retaining device is widely used on the market, which is manufactured according to the principle of a sucking disc as the legs of an octopus. This vacuum retaining device has a sucking disk similar to a saucer disposed upside down. The sucking disc is placed on a smooth surface (such as a glass surface or a tile surface). After the air inside the sucking disk is discharged, the interior volume of the sucking disk is forced to increase. The external pressure (i.e., atmospheric pressure) will be greater than the interior pressure of the sucking disk. Thus, the sucking disk is pressured by the atmospheric pressure, so that the vacuum retaining device can be adhered to the smooth surface.
Japanese Utility Model Publication No. So61-109367 (published on Jul. 11, 1986) discloses a vacuum retaining device. After a period of time, the sucking disc of this vacuum retaining device will be hardened to seriously affect its suction force. In particular, when the surface to be adhered has a slit or a serrate line, the sucking disk cannot form a complete vacuum wall so it is no longer able to adhere to the surface.
In order to solve the aforesaid problems of the prior art, an improved vacuum retaining device is developed, as disclosed in Japanese Utility Model Reg. No. 3014841 (granted on Jun. 7, 1995). This vacuum retaining device has a screw rod shaft installed at the upper portion of the center of the sucking disc, an arc press plate for the screw rod shaft to be inserted therein and covering the upper surface of the sucking disc, and a handle connected with the screw rod shaft extending out from the upper portion of the press plate. The edge of the sucking surface of the sucking disk is provided with adhesive which is a binding material having ductility (such as adhesive silicone).
It is a good attempt to use the binding material having ductility to enhance the adhesion of the sucking disk. However, the sucking disk is made of a soft material. When the center of the sucking disk is lifted toward the press plate to enlarge the interior volume of the sucking disk, the edge of the sucking disk may be deformed or it may result in a slight slide between the sucking surface and the surface to be adhered. Specially, if there is a serrate line on the surface to be adhered, the existing technique is unable to provide a perfect binding force.
Chinese Patent No. ZL200480029868.9 also discloses a vacuum retaining device. This vacuum retaining device includes a gel-type vacuum wall made of polyurethane. The vacuum wall extends outward from the bottom of a press plate to the edge of the press plate toward a surface to be adhered. The vacuum retaining device further has a press surface inclined toward the center of the press plate to join an upward slope of a sucking disk. When the press plate makes the interior of the sucking disk be a vacuum state, the slit or the serrate portion of the surface to be adhered can be blocked by the gel-type vacuum wall, so that the interior of the sucking disk is kept in a vacuum state. However, the vacuum retaining device fixed to the surface to be adhered is not limited to a long time. It may be fixed temporarily or changed to a different surface for reuse. When the foresaid vacuum retaining device is detached from the surface, it is necessary to use a screw rod fastening member to restore the interior volume of the enlarged sucking disk for the external air to enter the interior of the sucking disk, such that the vacuum retaining device can be detached from the surface. Although the gel-type vacuum wall made of polyurethane provides better adhesion and elongation to block the external air, it cannot be restored well after elongation and may have a deformation to affect the sealing effect when it is detached from the surface to be adhered repeatedly. A portion of the inclined press surface may disengage from the upward slope of the sucking disk. As a result, the air enters the interior of the sucking disk. Sometimes, a portion of the vacuum wall has been detached from the surface to be adhered, and the sucking disk located at the inner edge of the vacuum wall still adheres to the surface to be adhered. It is not easy to poke the edge of the sucking disk away from the surface to be adhered. For this reason, the vacuum retaining device cannot be fixed repeatedly and conveniently. Accordingly, the inventors of the present invention have devoted themselves based on their many years of practical experiences to solve these problems.